Method of making heat treated coated article using diamond-like carbon (DLC) coating and protective film

ABSTRACT

There is provided a method of making a heat treated (HT) coated article to be used in shower door applications, window applications, or any other suitable applications where transparent coated articles are desired. For example, certain embodiments of this invention relate to a method of making a coated article including a step of heat treating a glass substrate coated with at least a layer of or including diamond-like carbon (DLC) and an overlying protective film thereon. In certain example embodiments, the protective film may be of or include both (a) an oxygen blocking or barrier layer, and (b) a release layer. Following and/or during heat treatment (e.g., thermal tempering, or the like) the protective film may be removed. Other embodiments of this invention relate to the pre-HT coated article, or the post-HT coated article.

This application is a continuation-in-part (CIP) of U.S. Ser. No.11/699,080, filed Jan. 29, 2007, the entire disclosure of which ishereby incorporated herein by reference.

Certain embodiments of this invention relate to a method of making aheat treated (HT) coated article to be used in shower door applications,window applications, tabletop applications, or any other suitableapplications. For example, certain embodiments of this invention relateto a method of making a coated article including a step of heat treatinga glass substrate coated with at least a layer comprising diamond-likecarbon (DLC) and an overlying protective film thereon. In certainexample embodiments, the protective film may be of or include both (a)an oxygen blocking or barrier layer, and (b) a release layer. Followingand/or during heat treatment (e.g., thermal tempering, or the like) theprotective film may be entirely or partially removed. Other embodimentsof this invention relate to the pre-HT coated article, or the post-HTcoated article.

BACKGROUND OF THE INVENTION

Coated articles such as transparent shower doors and IG window units areoften heat treated (HT), such as being thermally tempered, for safetyand/or strengthening purposes. For example, coated glass substrates foruse in shower door and/or window units are often heat treated at a hightemperature(s) (e.g., at least about 580 degrees C., more typically fromabout 600-650 degrees C.) for purposes of tempering.

Diamond-like carbon (DLC) is sometimes known for its scratch resistantproperties. For example, different types of DLC are discussed in thefollowing U.S. Pat. Nos. 6,303,226; 6,303,225; 6,261,693; 6,338,901;6,312,808; 6,280,834; 6,284,377; 6,335,086; 5,858,477; 5,635,245;5,888,593; 5,135,808; 5,900,342; and 5,470,661, all of which are herebyincorporated herein by reference.

It would sometimes be desirable to provide a window unit or other glassarticle with a protective coating including DLC in order to protect itfrom scratches and the like. Unfortunately, DLC tends to oxidize andburn off at temperatures of from approximately 380 to 400 degrees C., asthe heat treatment is typically conducted in an atmosphere includingoxygen. Thus, it will be appreciated that DLC as a protective overcoatcannot withstand heat treatments (HT) at the extremely high temperaturesdescribed above which are often required in the manufacture of vehiclewindows, IG window units, glass table tops, and/or the like.

Accordingly, those skilled in the art will appreciate that a need in theart exists for a method of providing heat treated (HT) coated articleswith a protective coating (one or more layers) comprising DLC. A needfor corresponding coated articles, both heat treated and pre-HT, alsoexists.

BRIEF SUMMARY OF EXAMPLES OF INVENTION

Certain example embodiments of this invention relate to a method ofmaking a heat treated (HT) coated article to be used in shower doorapplications, window applications, tabletop applications, or any othersuitable application. For example, certain embodiments of this inventionrelate to a method of making a coated article including a step of heattreating a glass substrate coated with at least a layer comprisingdiamond-like carbon (DLC) and an overlying protective film thereon. Incertain example embodiments, the protective film may be of or includeboth (a) an oxygen blocking or barrier layer, and (b) a release layer.Following and/or during heat treatment (e.g., thermal tempering, or thelike) the protective film may be entirely or partially removed. Otherembodiments of this invention relate to the pre-HT coated article, orthe post-HT coated article.

An example advantage of using distinct and different oxygen-blocking andrelease layers in the protective film is that each layer of theprotective film can be optimized for its intended function.Consequently, the optimized performance of the protective film may beimproved and it can be made thinner if desired.

In certain example embodiments of this invention, there is provided amethod of making a heat treated coated article, the method comprising:providing a glass substrate; forming at least one layer comprisingdiamond-like carbon (DLC) on the glass substrate; forming a protectivefilm on the glass substrate over at least the layer comprising DLC, theprotective film include a release layer and an oxygen barrier layer, therelease layer and the oxygen barrier layer being of different materialand/or different stoichiometry relative to each other; heat treating theglass substrate with the layer comprising DLC and the protective filmthereon so that during the heat treating the protective film preventssignificant burnoff of the layer comprising DLC, wherein the heattreating comprises heating the glass substrate to temperature(s)sufficient for thermal tempering, heat strengthening, and/or heatbending; and exposing the protective film to a release liquid andremoving at least part of the protective film during and/or after saidheat treating.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross sectional view of a coated article, prior toand following heat treatment, according to an example embodiment of thisinvention.

FIG. 2 is a schematic cross sectional view of a coated article, prior toand following heat treatment, according to another example embodiment ofthis invention.

FIG. 3 is a schematic cross sectional view of a coated article, prior toand following heat treatment, according to another example embodiment ofthis invention.

FIG. 4 is a schematic cross sectional view of a coated article, prior toand following heat treatment, according to an example embodiment of thisinvention.

FIG. 5 is a schematic cross sectional view of a coated article, prior toand following heat treatment, according to another example embodiment ofthis invention.

FIG. 6 is a schematic cross sectional view of a coated article, prior toand following heat treatment, according to another example embodiment ofthis invention.

FIG. 7 is a schematic cross sectional view of a coated article, prior toand following heat treatment, according to another example embodiment ofthis invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Referring now more particularly to the accompanying drawings in whichlike reference numerals indicate like parts throughout the severalviews.

Certain example embodiments of this invention relate to methods ofmaking coated articles that may use heat treatment (HT), wherein thecoated article includes a coating (one or more layers) includingdiamond-like carbon (DLC). In certain instances, the HT may involveheating a supporting glass substrate, with the DLC thereon, totemperature(s) of from 550 to 800 degrees C., more preferably from 580to 800 degrees C. (which is well above the burn-off temperature of DLC).In particular, certain example embodiments of this invention relate to atechnique for allowing the DLC to withstand such HT withoutsignificantly burning off during the same. In certain embodiments, asacrificial protective film is formed on the glass substrate over theDLC so as to reduce the likelihood of the DLC burning off during HT.Thus, the majority (if not all) of the DLC remains on the glasssubstrate, and does not burn off, during the HT. Following HT, thesacrificial protective film (which may include one or more layers) mayor may not be removed in different embodiments of this invention.

In certain example embodiments, the sacrificial protective film may beof or include both (a) an oxygen blocking or barrier layer, and (b) arelease layer. An example advantage of using distinct and differentoxygen-blocking and release layers in film 17 is that each layer (17 aand 17 b) can be optimized for its intended function. Consequently, theoptimized performance of the sacrificial film 17 may be improved and itcan be made thinner if desired. In certain example embodiments,following HT the DLC inclusive layer protects against abrasion andcorrosion, and against adhesion of minerals in hard water (e.g., hasgood hard water cleanability).

FIG. 1 is a schematic cross sectional view of a coated article, beforeand after heat treatment, according to an example embodiment of thisinvention. Typically, the coated article on the left side of FIG. 1exists during a stage of manufacture prior to heat treatment (HT), butmay also exist post-HT in certain instances. The coated article shown inFIG. 1 includes glass substrate 1, DLC inclusive layer 11, andsacrificial protective film 17 which may include one or more layers. Incertain example embodiments, the protective film 17 includes first andsecond layers 17 a and 17 b which may be of the same or differentmaterial(s).

Glass substrate 1 is typically of or includes soda-lime-silica glass,although other types of glass may be used in certain instances.

DLC inclusive layer 11 may be from about 5 to 1,000 angstroms (Å) thickin certain example embodiments of this invention, more preferably from10-300 Å thick, and most preferably from 20 to 65 Å thick, possibly fromabout 25-50 Å thick, with an example thickness being about 30 angstroms.In certain example embodiments of this invention, DLC layer 11 may havean average hardness of at least about 10 GPa, more preferably at leastabout 20 GPa, and most preferably from about 20-90 GPa. Such hardnessrenders layer(s) 11 resistant to scratching, certain solvents, and/orthe like. Layer 11 may, in certain example embodiments, be of or includea special type of DLC known as highly tetrahedral amorphous carbon(t-aC), and may be hydrogenated (t-aC:H) in certain embodiments. Incertain hydrogenated embodiments, the t-aC type or any other suitabletype of DLC may include from 1 to 30% hydrogen, more preferably from5-20% H, and most preferably from 10-20% H. This t-aC type of DLCincludes more sp³ carbon-carbon (C—C) bonds than sp² carbon-carbon (C—C)bonds. In certain example embodiments, at least about 30% or 50% of thecarbon-carbon bonds in DLC layer 11 may be sp³ carbon-carbon (C—C)bonds, more preferably at least about 60% of the carbon-carbon bonds inthe layer 11 may be sp³ carbon-carbon (C—C) bonds, and most preferablyat least about 70% of the carbon-carbon bonds in the layer 11 may be sp³carbon-carbon (C—C) bonds. In certain example embodiments of thisinvention, the DLC may have an average density of at least about 2.4gm/cm³, more preferably at least about 2.7 gm/cm³. Example linear ionbeam sources that may be used to deposit DLC inclusive layer 11 onsubstrate 1 include any of those in any of U.S. Pat. Nos. 6,261,693,6,002,208, 6,335,086, or 6,303,225 (all incorporated herein byreference). When using an ion beam source to deposit layer(s) 11,hydrocarbon feedstock gas(es) (e.g., C₂H₂), HMDSO, or any other suitablegas, may be used in the ion beam source in order to cause the source toemit an ion beam toward substrate 1 for forming layer(s) 11. It is notedthat the hardness and/or density of layer(s) 11 may be adjusted byvarying the ion energy of the depositing apparatus.

DLC layer 11 allows the coated article to be more scratch resistant thanif the DLC 11 were not provided. It is noted that while layer 11 is onglass substrate 1 in certain embodiments of this invention, additionallayer(s) may or may not be under layer 11 between the substrate 1 andlayer 11 in certain example embodiments of this invention. Thus, thephrase “on the substrate” as used herein is not limited to being indirect contact with the substrate as other layer(s) may still beprovided therebetween.

For example and without limitation, the layer 11 of or including DLC maybe any of the DLC inclusive layers of any of U.S. Pat. Nos. 6,592,993;6,592,992; 6,531,182; 6,461,731; 6,447,891; 6,303,226; 6,303,225;6,261,693; 6,338,901; 6,312,808; 6,280,834; 6,284,377; 6,335,086;5,858,477; 5,635,245; 5,888,593; 5,135,808; 5,900,342; or 5,470,661 (allof these patents hereby being incorporated herein by reference), oralternatively may be any other suitable type of DLC inclusive layer. DLCinclusive layer 11 may be hydrophobic (high contact angle), hydrophilic(low contact angle), or neither, in different embodiments of thisinvention. The DLC 11 may or may not include from about 5-30% Si, morepreferably from about 5-25% Si, and possibly from about 10-20% Si incertain example embodiments of this invention. Hydrogen may also beprovided in the DLC in certain instances.

Sacrificial protective film 17 is provided in order to protect DLC layer11 during HT. If film 17 were not provided, the DLC 11 wouldsignificantly oxidize during HT and burn off, thereby rendering thefinal product defenseless against scratching. However, the presence ofsacrificial protective film 17 prevents or reduces the amount of oxygenwhich can reach the DLC 11 during HT from the surrounding atmosphere,thereby preventing the DLC from significantly oxidizing during HT. As aresult, after HT, the DLC inclusive layer 11 remains on the glasssubstrate 1 in order to provide scratch resistance and/or the like. Incertain example embodiments, the protective film 17 includes both anoxygen blocking or barrier layer 17 a, and a release layer 17 b.

It has surprisingly been found that the use zinc and/or zinc oxide insacrificial protective film 17 is/are especially beneficial with respectto reducing and/or preventing oxygen diffusion into the DLC during HT.In the FIG. 1 example embodiment of this invention, the protective film17 includes a first zinc inclusive layer 17 a and a second zinc oxideinclusive layer 17 b. The first zinc inclusive layer 17 a may bemetallic, substantially metallic, or substoichiometric zinc oxide indifferent example embodiments of this invention; whereas the second zincoxide inclusive layer 17 b may be of or including zinc oxide in certainexample embodiments of this invention. In certain example embodiments,layer 17 a is more metallic than layer 17 b. In other words, layer 17 bcontains more oxygen than does layer 17 a. Thus, layer 17 a is able tofunction is as a release layer whereas layer 17 b is able to function asan oxygen blocking or barrier layer. An oxygen “blocking” or “barrier”layer means that the layer blocks significant amounts of oxygen fromreaching the DLC during HT.

In certain example embodiments of this invention, layer 17 a may be ofor include ZnO_(y) and layer 17 b may be of or include ZnO_(x), wherex>y (i.e., layer 17 b contains more oxygen than layer 17 a). Moreover,in certain example embodiments of this invention, y is from about 0 to0.9, more preferably from about 0.1 to 0.9, even more preferably fromabout 0.1 to 0.8, and possibly from about 0.1 to 0.7. Meanwhile, incertain example embodiments of this invention, x is greater than y, andx is from about 0.3 to 1.0, more preferably from about 0.3 to 0.99, evenmore preferably from about 0.5 to 0.95, and possibly from about 0.6 to0.90. Thus, it will be appreciated that in certain example instances,both layers 17 a and 17 b may be of or include zinc oxide, and bothlayers 17 a and 17 b may be substoichiometric.

Advantageously, it has been found that the use of zinc oxide layer 17 athat is more metallic than zinc oxide layer 17 b surprisingly permitsmore efficient and easier removal of the protective film 17 duringand/or following heat treatment (HT). In other words, layer 17 a is arelease layer. The different compositions of zinc oxide inclusive layers17 a and 17 b is used to cause different stresses in layers 17 a and 17b, which stresses are manipulated so as to allow the film 17 to be moreeasily removed during and/or following HT. In particular, more metalliczinc oxide based layer 17 a may be considered a release layer forallowing the film 17 to be easily removed from the DLC or substrateduring and/or after HT due to its reduced or no oxygen content, whereasthe less metallic (and more oxided) zinc oxide based layer 17 b may beconsidered an oxygen blocking or barrier layer that reduces or preventsthe DLC from burning off and/or oxidizing during HT. Note also that anygettering layer may be considered an oxygen barrier layer in certainexample instances. In certain example instances, the more oxidic layer17 b may be considered a blocking/protection layer, for protecting thesofter less oxidic getting/barrier layer 17 a during heat treatment andotherwise. Zinc oxide is a highly advantageous material for film 17because it can be easily removed (e.g., using water and/or vinegar)during and/or following HT in a non-toxic manner.

As noted above, one or both of layers 17 a and 17 b when of or includingzinc and/or zinc oxide may be substoichiometric. This is advantageousfor oxygen gettering purposes during HT. If the zinc oxide of the entirefilm 17 is too oxided (i.e., fully stoichiometric) prior to HT, thenoxygen can diffuse through the zinc oxide. However, thesubstoichiometric nature of layer(s) 17 a and/or 17 b permits the zinctherein to getter oxygen during HT, so that at least layer 17 a (andpossibly layer 17 b) does not burn off during HT. It is noted that upperzinc oxide based layer 17 b may or may not burn off (entirely orpartially) during HT in different example embodiments of this invention.It is noted that another example advantage of substoichiometric zincoxide (compared to fully stoichiometric zinc oxide) is that it can bedeposited (e.g., via sputtering or the like) more quickly. One or bothof layers 17 a, 17 b may be sputter-deposited in a substoichiometricform, in any suitable manner; e.g., by varying oxygen gas flow in thesputtering chamber(s). For example, as one non-limiting example, layer17 a may be sputter-deposited using 10 ml/kW (regarding content ofoxygen gas flow), whereas layer 17 b may be sputter-deposited using 12ml/kW (with remainder of the gas being Ar or the like) in exampleinstances.

Note that one or both of zinc oxide layers 17 a and 17 b may be dopedwith other materials such as Al, N, Zr, Ni, Fe, Cr, Ti, Mg, mixturesthereof, or the like, in certain example embodiments of this invention.

In certain example embodiments of this invention, release layer 17 a(e.g., of zinc or substoichiometric zinc oxide) may be deposited (e.g.,via sputtering) so as to be from about 50-20,000 Å thick, morepreferably from about 50-3,000 Å thick, even more preferably from about100-1,000 Å thick, with an example thickness being from about 100-300 Å.In certain embodiments, zinc oxide inclusive layer 17 b may be deposited(e.g., via sputtering) so as to be from about 200-10,000 Å thick, morepreferably from about 500-5,000 Å thick, more preferably from about1,000-3,000 Å thick, with an example thickness being about 2,000 Å. Moremetallic layer 17 a may be thicker than less metallic layer 17 b incertain example embodiments of this invention; layer 17 a may be atleast twice as thick as layer 17 b in certain example instances prior toHT. A preferred thickness of overall sacrificial film 17 in certainexample embodiments is less than about 10,000 Å, more preferably lessthan about 3,000 Å, and most preferably less than about 1,000 Å.

FIG. 2 illustrates another example embodiment of this invention. TheFIG. 2 embodiment is the same as the FIG. 1 embodiment discussed above,except that in the FIG. 2 embodiment a barrier layer 6 is providedbetween the glass substrate 1 and the DLC inclusive layer 11. Barrierlayer 6 may be a dielectric in certain example embodiments of thisinvention. Optional barrier layer 6 is for preventing or reducing oxygenand/or sodium (Na) from migrating from the glass 1 into the DLC 11during HT. In this respect, such an optional barrier layer 6 may improvethe overall optical characteristics of the coated article post-HT.Barrier layer 6 may be of or include silicon oxide, silicon nitride,silicon oxynitride, and/or the like, although other barrier materialsmay also be used. Barrier layer(s) 6 is formed on the glass substrate 1via sputtering, or via any other suitable technique. Barrier layer 6 maybe from about 10 to 1,000 Å thick in certain example embodiments, morepreferably from 50 to 500 Å thick, and most preferably from 50 to 200 Åthick. It is noted that a barrier layer(s) 6 may also be provided inother example embodiments of this invention, for instance in any ofFIGS. 4-7 if desired between the DLC 11 and the glass substrate 1.

FIG. 3 illustrates another example embodiment of this invention. TheFIG. 3 embodiment is the same as the FIG. 1 embodiment (or even the FIG.2 embodiment if barrier layer 6 is used, which may be the case in theFIG. 3 embodiment), except that instead of two discrete layers 17 a and17 b the protective film 17 is made of one layer that is oxidationgraded (continuously or non-continuously) through its thickness. In theFIG. 3 embodiment, the film 17 is provided in a manner so that the film17 includes more oxygen at a location further from the DLC layer 11 thanat another location in the film closer to the DLC layer 11. Note thatthe film 17 in the FIG. 1-2 embodiments may also be considered oxidationgraded because the overall film 17 is more oxided in layer 17 b furtherfrom the DLC 11 than in layer 17 a closer to the DLC 11. However, in theFIG. 3 embodiment, it is also possible for continuous or substantiallycontinuous oxidation grading to occur through the entire orsubstantially entire film 17 in certain example instances.

An example process of manufacturing a coated article will now bedescribed, with reference to FIGS. 1-3. Initially, glass substrate 1 isprovided, and at least one barrier layer 6 (e.g., silicon oxide, siliconnitride, silicon oxynitride, or the like) may optionally be sputtered ona surface thereof. Optionally, a multi-layer solar control coating (notshown) may be deposited (e.g., via sputtering) on the surface of theglass substrate 1 opposite the barrier layer 6. At least one layer 11 ofor including DLC is deposited (e.g., via ion beam deposition) on theglass substrate 1, over at least the optional barrier layer 6 ifpresent. Then, protective film 17, e.g., including layers 17 a and 17 b,is deposited on the substrate 1 over the DLC inclusive layer 11.Protective film 17 may be deposited via sputtering, CVD, ion beamdeposition, or any other suitable technique. Optionally, a thinprotective layer comprising DLC, silicon nitride, aluminum nitride, orsilicon aluminum nitride (not shown), may be provided over sacrificialfilm 17 prior to HT, for durability and/or oxygen barrier purposes.

As shown in FIGS. 1-2, the glass substrate 1 with films 6 (optional), 11and 17 thereon is then heat treated (HT) for purposes of thermaltempering, heat bending, heat strengthening, and/or the like. At leastpart of this HT may be conducted, for example, in an atmosphereincluding oxygen as known in the art at temperature(s) of from 550 to800 degrees C., more preferably from 580 to 800 degrees C. (i.e.,temperature(s) above the burn-off temperature of DLC). The HT may lastfor at least one minute, more preferably from 1-10 minutes, in certainexample non-limiting embodiments of this invention. During HT, thepresence of protective film 17 protects DLC inclusive layer 11 from theHT and prevents layer 11 from significantly oxidizing and/or burning offdue to significant oxidation during the HT. While in some instances someof layer 11 may burn off during HT, the majority if not all of DLCinclusive layer 11 remains on the substrate 1 even after the HT due tothe presence of protective film 17.

A significant advantage associated with using zinc and/or zinc oxide infilm 17 is its ease of removal after HT. Protective layers such assilicon nitride are sometime undesirable since they require complexetching in order to remove the same after HT. On the other hand, it hasbeen found that when film 17 is made of zinc and/or zinc oxide, solublein vinegar and/or water (possibly only water with no vinegar required incertain preferred embodiments), the application of vinegar and/or waterallows portions of film 17 remaining after HT to be easily removed in anon-toxic manner. Again, in certain example embodiments, it is possibleto remove the zinc oxide with only water (no vinegar needed) in certaininstances, which is advantageous from a cost and processing point ofview. In certain example instances, rubbing with such liquids may beespecially beneficial in removing film 17 after HT when the coatedarticle is still warm therefrom (e.g., when the film 17 is from about80-200 degrees C., more preferably from about 100-180 degrees C.;although the removal of film 17 may also take place at room temperaturein certain example embodiments).

After film 17 has been removed, the remaining coated article is shown atthe right side of FIGS. 1-2, and includes an outer layer comprisingscratch resistant DLC. The aforesaid processes are advantageous in thatthey provide a technique for allowing a coated article including aprotective DLC inclusive layer 11 to be heat treated without the DLClayer 11 burning off during such HT. In other words, it becomes possibleto provide a protective DLC inclusive layer 11 on a heat treated (e.g.,thermally tempered) product in a commercially acceptable manner.

FIG. 4 is a cross sectional view of an example embodiment of thisinvention that is similar to FIGS. 1-2, except that release layer 17 aand oxygen blocking layer 17 b need not be of zinc oxide. A barrierlayer 6 (discussed above) may or may not be provided between the glassand the DLC in the FIG. 4 embodiment (although it is not shown in thefigure).

The oxygen blocking or barrier layer 17 b may be of or include amaterial selected from the group consisting of: zinc oxide, siliconcarbide, aluminum nitride, boron oxide, aluminum oxide, aluminumoxynitride, silicon nitride, silicon oxide, silicon oxynitride, andmixtures thereof. Preferred materials for the oxygen blocking or barrierlayer 17 b are aluminum nitride and silicon carbide in certain exampleembodiments. In certain example embodiments, the layer 17 b is designedto be about as hard and/or durable as glass.

The release layer 17 a may be of any suitable material that dissolves orreadily reacts with water, vinegar, or bleach. Release layer 17 apreferably has a melting point (or dissociation temperature) above 580or 600 degrees C. in certain example embodiments. The release layer 17 amay be of or include oxides, suboxides, nitrides and/or subnitrides ofboron, titanium boride, magnesium, zinc, and mixtures thereof. Preferredmaterials for the release layer 17 a in certain example embodiments aresuboxides of zinc, magnesium and/or titanium boride. Note that the term“oxide” as used herein is broad enough to encompass suboxides.

In certain example embodiments, release layer 17 a is more dissolvablethan is layer 17 b in water, vinegar, bleach and/or the like. Moreover,in certain example embodiments, oxygen barrier layer 17 b is more of abarrier to oxygen and/or is harder than is release layer 17 a. Examplarycoatings may produce high quality post-HT and post-release DLC, withgood scratch resistance and good hard water cleanability. The releaselayer 17 a and/or the oxygen barrier layer 17 b may be deposited viasputtering, or any other suitable technique, in different exampleembodiments of this invention.

FIG. 5 shows an example embodiment where the release layer 17 a is of orincludes a suboxide of magnesium (MgO_(x)), and the oxygen blocking orbarrier layer 17 b is of or includes silicon carbide. Optionally, abarrier layer 6 may be provided between the DLC 11 and the glasssubstrate 1 in certain instances of this embodiment, for reducing sodiummigration during or due to HT. After heat treatment or HT (e.g.,tempering), the product is exposed to a mildly reactive liquid (e.g.,water, vinegar, dilute ammonia and/or bleach), and the liquid penetratesthrough to the release layer 17 a via pinholes or grain boundaries inthe overlying layer(s) and causes the release layer to disband from theDLC 11. Thus, the release layer 17 a and the oxygen barrier layer 17 bare removed following the HT. Hot water is a particularly good releaseliquid for use with the materials shown in the FIG. 5 embodiment.Example thickness are as follows in this example embodiment: barrierlayer 6 of silicon nitride or silicon oxynitride formed by sputteringabout 125 or 150 Å thick; DLC layer 11 about 50 Å thick; MgOx layer 17 aabout 190 Å thick, and SiC layer 17 b about 280 Å thick.

FIG. 6 shows an example embodiment where the release layer 17 a is of orincludes a suboxide of zinc (ZnO_(x)), and the oxygen blocking orbarrier layer 17 b is of or includes aluminum nitride (AlN). Optionally,a barrier layer 6 may be provided between the DLC 11 and the glasssubstrate 1 in certain instances of this embodiment, for reducing sodiummigration during or due to HT. After heat treatment or HT (e.g.,tempering), the product is exposed to a mildly reactive liquid (e.g.,water, vinegar, dilute ammonia and/or bleach), and the liquid penetratesthrough to the release layer 17 a via pinholes or grain boundaries inthe overlying layer(s) and causes the release layer to disband from theDLC 11. Thus, the release layer 17 a and the oxygen barrier layer 17 bare removed following the HT. Vinegar is a particularly good releaseliquid for use with the materials shown in the FIG. 6 embodiment.Example thickness are as follows in this example embodiment: barrierlayer 6 of silicon nitride about 150 Å thick; DLC layer 11 about 50 Åthick; ZnOx layer 17 a about 500 Å thick, and AlN layer 17 b about 200 Åthick.

FIG. 7 shows an example embodiment where the release layer 17 a is of orincludes a suboxide of Mg (MgO_(x)), and the oxygen blocking or barrierlayer 17 b is of or includes aluminum nitride (AlN). Optionally, abarrier layer 6 may be provided between the DLC 11 and the glasssubstrate 1 in certain instances of this embodiment, for reducing sodiummigration during or due to HT. After heat treatment or HT (e.g.,tempering), the product is exposed to a mildly reactive liquid (e.g.,water, vinegar, dilute ammonia and/or bleach), and the liquid penetratesthrough to the release layer 17 a via pinholes or grain boundaries inthe overlying layer(s) and causes the release layer to disband from theDLC 11. Thus, the release layer 17 a and the oxygen barrier layer 17 bare removed following the HT. Hot water is a particularly good releaseliquid for use with the materials shown in the FIG. 7 embodiment.Example thickness are as follows in this example embodiment: DLC layer11 about 50 Å thick; MgOx layer 17 a about 230 Å thick, and AlN layer 17b about 200 Å thick.

According to certain example embodiments of this invention, coatedarticles herein lose no more than about 15% of their visibletransmission due to HT, more preferably no more than about 10%.Moreover, monolithic coated articles herein preferably have a visibletransmission after HT of at least about 50%, more preferably of at leastabout 60 or 75%.

In any of the embodiments discussed above (e.g., see FIGS. 1-7), it isalso possible to provide an optional scratch resistant layer (e.g., ofor including SiC or DLC—not shown) over the layer 17 b.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

The invention claimed is:
 1. A method of making a heat treated coatedarticle, the method comprising: having a glass substrate with at leastone layer comprising diamond-like carbon (DLC) on the glass substrateand a protective film on the glass substrate over at least the layercomprising DLC, the protective film including a release layer from100-1,000 Å thick and an oxygen barrier layer, the release layer and theoxygen barrier layer being of different material and/or differentstoichiometry relative to each other and the release layer being betweenat least the layer comprising DLC and the oxygen barrier layer, andwherein the oxygen barrier layer comprises aluminum nitride; heattreating the glass substrate with the layer comprising DLC and theprotective film thereon so that during the heat treating the protectivefilm prevents significant burnoff of the layer comprising DLC, whereinthe heat treating comprises heating the glass substrate totemperature(s) sufficient for thermal tempering, heat strengthening,and/or heat bending; and exposing the protective film to a releaseliquid and removing at least part of the protective film during and/orafter said heat treating.
 2. The method of claim 1, wherein the releaselayer comprises an oxide of one or more of boron, titanium boride,magnesium and/or zinc.
 3. The method of claim 1, wherein the releaselayer comprises an oxide of Zn and/or Mg.
 4. The method of claim 3,wherein the release layer comprises a suboxide of Zn and/or Mg.
 5. Themethod of claim 1, wherein the oxygen barrier layer consists essentiallyof aluminum nitride.
 6. The method of claim 1, wherein the release layercomprises zinc oxide.
 7. The method of claim 1, wherein the releaselayer consists essentially of zinc oxide which optionally may be dopedwith aluminum.
 8. The method of claim 1, wherein, in the protectivefilm, the release layer is more metallic than is the oxygen barrierlayer.
 9. The method of claim 1, wherein the release layer compriseszinc oxide that is oxidation graded in a continuous or non-continuousmanner prior to the heat treating so that prior to the heat treating thelayer has more oxygen at a location further from the layer comprisingDLC than at a location closer to the layer comprising DLC.
 10. Themethod of claim 1, wherein the layer comprising DLC is formed via an ionbeam.
 11. The method of claim 1, wherein the protective film is at leastpartially formed via sputtering.
 12. The method of claim 1, furthercomprising forming a barrier layer comprising silicon oxide and/orsilicon nitride on the glass substrate so as to be located between atleast the glass substrate and the layer comprising DLC.
 13. The methodof claim 1, wherein the heat treating comprises heating the glasssubstrate with the layer comprising DLC and the protective film thereonusing at least temperature(s) of at least 550 degrees C.
 14. The methodof claim 1, wherein the heat treating comprises heating the glasssubstrate with the layer comprising DLC and the protective film thereonusing at least temperature(s) of at least 580 degrees C.
 15. The methodof claim 1, wherein the layer comprising DLC comprises amorphous DLC andhas more sp³ carbon-carbon bonds than sp² carbon-carbon bonds.
 16. Themethod of claim 1, wherein the layer comprising DLC has an averagehardness of at least 10 GPa.
 17. The method of claim 1, wherein thelayer comprising DLC has an average hardness of at least 20 GPa.
 18. Themethod of claim 1, wherein the layer comprising DLC has a density of atleast about 2.7 gm/cm³, and wherein the layer comprising DLC ishydrogenated.
 19. The method of claim 1, wherein the layer comprisingDLC is hydrogenated.
 20. The method of claim 1, wherein the coatedarticle is substantially transparent and is adapted to be used as ashower door.
 21. The method of claim 1, wherein after said removing stepat least part of the layer comprising DLC is exposed so as to be anoutermost layer of the coated article.
 22. A method of making a heattreated coated article, the method comprising: having a glass substratewith at least one layer comprising diamond-like carbon (DLC) on theglass substrate and a protective film on the glass substrate over atleast the layer comprising DLC, the protective film including a releaselayer and an oxygen barrier layer, wherein the release layer compriseszinc oxide and the oxygen barrier layer comprises aluminum nitride; andheat treating the glass substrate with the layer comprising DLC and theprotective film thereon so that during the heat treating the protectivefilm prevents significant burnoff of the layer comprising DLC, whereinthe heat treating comprises heating the glass substrate totemperature(s) sufficient for thermal tempering, heat strengthening,and/or heat bending.